RANS Simulation of Hydrogen Flame Propagation in an Acceleration Tube: Examination of k-ω SST Model Parameters

Due to practical computational resource limits, current simulations of premixed turbulent combustion experiments are often performed using simplified turbulence treatment. From all available RANS models, k-ε and k-ω SST are the most widely used. k-ω SST model is generally expected to be more accurate in bounded geometries, since it corresponds to k-ε model further from the walls, but switches to more appropriate k-ω model near the walls. However, k-ε is still widely used and in some instances is shown to provide better results. In this paper, we perform RANS simulations of premixed hydrogen flame propagation in an acceleration tube using k-ε and k-ω SST models. Accuracy of the models is assessed by comparing obtained results with the experiment. In order to better understand differences between k-ε and k-ω-SST results, parameters of main k-ω-SST model features are examined. The distribution of the blending functions values and corresponding zones of are analysed in relation to flame position and resulting observed propagation velocity. We show that, in the simulated case, biggest difference between k-ω-SST and k-ε model results can be attributed to turbulent eddy viscosity limiting by shear strain rate in the k-ω-SST model.